Refrigeration systems, used for marine containers et cetera to provide cooling of the inside of the container compartments, have been known in the art for many years. In a marine-container refrigeration system, air may not be available as a cold heat source due to the shipboard equipment. To cope with this, there are proposed refrigeration systems such as one disclosed in JP-A-2004-340525. This refrigeration system, which is equipped with an air-cooled condenser and a water-cooled condenser, operates, selectively in response to the container installation situation, either in an air-cooled operation mode in which the refrigerant is condensed using air as a cold heat source or in a water-cooled operation mode in which the refrigerant is condensed using cooling water as a cold heat source.
More specifically, the refrigeration system is provided with a refrigerant circuit (60) (see FIG. 6). The refrigerant circuit (60) includes a compressor (61), an air-cooled condenser (62), a water-cooled condenser (63), an electronic expansion valve (64), and an evaporator (65) which are connected in series to operate a vapor compression refrigeration cycle. The air-cooled condenser (62) is arranged outside the container compartment. An air-cooled condenser fan (66) is installed in the vicinity of the air-cooled condenser (62). On the other hand, the water-cooled condenser (63) is configured such that it is suppliable with cooling water. In addition, the evaporator (65) is arranged within the container compartment. An evaporator fan (67) is installed in the vicinity of the evaporator (65).
When the refrigeration system operates in the air-cooled operation mode, the air-cooled condenser fan (66) and the evaporator fan (67) are turned on and the supply of cooling water to the water-cooled condenser (63) is stopped. After'refrigerant compressed in the compressor (61) is sent to the air-cooled condenser (62), heat exchange takes place in the air-cooled condenser (62) between outside compartment air supplied by the air-cooled condenser fan (66) and the refrigerant, and the refrigerant gives up heat to the outside compartment air and is condensed. Thereafter, the refrigerant passes as it is through the water-cooled condenser (63), is decompressed in the electronic expansion valve (64), and flows into the evaporator (65). Heat exchange takes place in the evaporator (65) between inside compartment air supplied by the evaporator fan (67) and the refrigerant, and the refrigerant absorbs heat from the inside compartment air and is evaporated. As a result, the air in the container compartment is cooled. The refrigerant evaporated in the evaporator (65) is drawn into and again compressed by the compressor (61) up to a predetermined pressure.
On the other hand, during the water-cooled operation mode, the air-cooled condenser fan (66) is turned off, and at the same time that the evaporator fan (67) is turned on, cooling water is supplied to the water-cooled condenser (63). Accordingly, refrigerant compressed in the compressor (61) is not substantially condensed in the air-cooled condenser (62), but it gives up heat to the supplied cooling water in the water-cooled condenser (63) and is condensed. The refrigerant condensed in the water-cooled compressor (63) flows and passes through the electronic expansion valve (64) and then through the evaporator (65), and is used to provide cooling of the inside of the container compartment, as in the air-cooled operation mode.